Lubricant



ilniteri States Patent O LUBRICANT Wilhelm Dietrich, Fritz Wetter, and Hans Joachim Mertens, Marl, Westphalia, Germany, assignors to Chemische Werke Hiils Aktiengesellschaft, a corporation of Germany No Drawing. Application August 3, 1953 Serial No. 372,147

lubricant additives of the most varied composition for normally as Well as highly loaded or so called E. 'P.

mechanisms and for internal combustion engines. Ordinary mineral lubricating oils, due 'to their tendency to form oxidation products and residues and in spite of their proportionately higher solidifying temperatures and lower viscosities are often used only "for lubrication purposes involving low lubrication requirements. Protective lubricating films can be obtained only imperfectly With normal mineral oil lubricants in many instances where high pressure, high speed of rotation and high temperature are involved. For this reason in such cases the ordinary mineral oil lubricants are substituted in part by synthetic products or compounds are added to the mineral lubricating oils which at high temperatures form tough adherent lubricating films which prevent contact of the moving metal surfaces. The addition of the 'socalled additives to the mineral oils is an attempt to improve their properties, that is, to confer upon them new properties. A large number of compounds such as polymers of olefines, cracked hydrocarbons, alkylated aromatic and naphthenic compounds and esters of higher alcohols have been used as lubricants or as lubricant additives. Other lubricants are the polyglycols such as those of ethylene, propylene and butylene and mixtures thereof. These polyglycols are sometimes etherified or esterified or made to contain hetero atoms in their molecules for the purpose of giving them the required lubricity or improving their lubricity.

It has been found that polyalkylene glycolxanthic acid derivaties of the general formula in which R stands for an aliphatic, cycloaliphatic, araliphatic, aromatic, heterocyclic or acyl residue which may be substituted, X stands for a member of the group consisting of hydrogen and ether and ester radicals, n and q are whole numbers from 1 to 20 and m and p are whole numbers from 2 to 4, are lubricants having excellent extreme pressure lubricating properties and are useful as additives to mineral oils and to polyalkylene glycols to which they impart substantial extreme pressure lubricity. The said derivatives may be used alone as additives or in combination with known lubricant additives.

The said polyalkylene glycol xanthic acid derivatives may be obtained by first treating 1 molecular proportion of an organic hydroxyl or sulfhydryl compound with 120 moles of an alkylene oxide in the presence of from 1 to 2% by Weight of sodium or an alkali metal hydroxide, calculated on the organic hydroxyl or sulfhydryl compound, at 120--l50 C.

Suitable representative hydroxyl compounds are for example butyl alcohols, octyl alcohols, lauryl alcohols, glycols such as ethylene, propylene and butylene glycols, hexane diols, polyglycols, isobutyl alcohol, isooctyl alcohol, 2 methyl 1,3 pentane-diol, 2 ethylbutyl-l,3- propane-diol, dicyclopentadienol, benzyl alcohol, phenylethyl alcohol, phenols, hexylphenols, octylphenols, condensation products of isobutylene and cresols, cyclohexanol, furfuryl alcohol; also the alcohols formed by catalytic hydrogenation of carbon dioxide and the alcohols formed by the addition of water to olefines formed by cracking hydrocarbons.

Instead of the above mentioned hydroxyl compounds the corresponding sulfhydryl compounds may be used as the starting material. Suitable alkylen'e oxides are for example ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, isobutylen'e oxide and mixtures thereof.

To convert the oxalkylated organic hydroxyl or sulfhydryl compound into the corresponding xanthic acid derivatives, the oxalkylated compound is treated with carbon disulfide and alkali metal hydroxide in molecular ratio at 20-30 C. and with stirring preferably in the present of diluents such as benzene because the xanthogenate has a thickly liquid consistency.

The xanthogenate obtained is then-reacted with alkylene oxide using from 1-20 molecules thereof per molecule of the xanthogenate at a temperature lower than that at which the xanthogenate was produced, for instance at 40*50 C.

The properties of the sulfur containing condensation products are influenced to a considerable degree by the choice of the hydroxyl or sulfhydryl compound and by the number of hydroxyl or sulfhydryl groups, by the r chain length of the aliphatic group or the introduced aromatic residue, by variation of the length of the polyalkylene glycol compound, by'the reaction of the formed polyalkylene xanthogenate with varying amounts of alkylene oxide as Well as by etherifying or esterifying the hydroxyl groups, not only in relation to their solubility but also with respect to their solidifying and flash points, their viscosities and temperative behavior and odor. The condensation products are more or less viscous orangeyellow to dark brown oils. They have the characteristic odor for xanthic acid derivatives. The odor is improved by treatment with etherifying and esterifying agents and generally at the same time their solubility in mineral oils is increased. It is possible to use other additives with the condensation products such as agents for improving the color, antioxidation agents, foam preventing agents, solidifying point lowering agents, viscosity improving agents and other agents for improving the extreme pressure lubricating properties of lubricants.

Ordinary mineral lubricating oils having average lubricating properties may, by the addition of the condensation products in small amounts which depending upon the manner and character of the use of the oil may go as high as 10% of the Weight of the mineral oil and this addition may even be exceeded, be so greatly improved in their lubricating properties that they exhibit the properties of high value lubricating oils with extreme pressure lubricating properties and become versatile and especially adapted for use for lubricating highly loaded mechanisms and internal combustion engines. Morcover the higher grades of mineral oil lubricants which already contain additives for improving their lubricating properties may by the addition of small amounts up to 5% of the new compounds be considerably improved whereby the mentioned addition, depending upon the kind and character of the already present additive may be exceeded. Besides the condensates exhibit antioxidant properties.

For determining the lubricity of the condensation products the four ball testing apparatus (FBTA) was used (see Engineering, July 14, 1933, pages 46-47, and Engineering, vol. CXLIV, July 2, 1937, pages l-2). The above mentioned condensation products are excellent lubricants having noteworthy extreme pressure lubricating properties, the FBTA number being over 500, and even up to 700.

The behavior of a few of the condensation products is given in more detail in the following examples. Their uses are not limited to those mentioned in the examples.

Example 1 If small amounts of the dithiocarbonic acid-O-(nonapropylene glycol ethylhexylether-)-S.-(1,2-propylene-glycol butylether) are added to a mineral lubricating oil having a specific gravity of 0.78 at 15/4", a viscosity ranging from 47.2 E to 8.49 E Within the temperature range from 20 C. to 50 C., a viscosity index of 104 and a solidifying point of -12 C., the FBTA value is considerably increased. The effect of additions of the above mentioned compound is shown in the following table.

Addition: FBTA loading None 150 1.00% 230 1.75% 270 5.00% 290 10.00% 390 Wear values in mm.

20 minutes 40 minutes 80 minutes no addition 1% of addition.. 2.5% addition The wear values for a two hour run at 15 kg. load with the same mineral lubricating oil with 2.5% of the same dithiocarbonic acid compound was 0.090 mm.

The dithiocarbonic acid-O-(nona-propylene glycolethylhexylether-)-S-(1,2-propylene-glycol butylether referred to above is obtained by reacting 130 parts of 2- ethylhexanol with an addition of 2-3 parts of sodium at l30-l50 C. under normal pressure with 465-522 parts of propylene oxide. 56 parts of potassium hydroxide are added and then after cooling to 20 C., 76 parts of carbon disulfide are slowly introduced with stirring. After a short time, at a temperature up to as high as 50 C., 70 parts of propylene oxide are gradually introduced. For increasing the solubility in liquid hydrocarbons the reaction product is etherified by the addition of 58 parts of potassium hydroxide, 200 parts of water and 140 parts of butylbromide with stirring followed by heating to boiling for 4 to 5 hours. After separating potassium bromide the reaction mixture is freed of water, neutralized and dried.

Example 2 The following data shows the results of the addition of 5 parts by weight of the specified compounds to 95 parts by weight of a mineral lubricating oil, the same as that used in Example 1, which has a FBTA value of 150.

Bis-dithiocarbonic acid-O-(tripropylene glycol-2-methyl-l,3-pentadiol ether-)-S-(tripropy1ene glycol acetic acid ester) FBTA value 330. This compound is obtained by reacting 118 parts of 2-methyl-l,3-pentane diol, after the addition thereto of 1 part of sodium with 174 parts of propylene oxide at 130 C.-l40 C. After the addition of 200 parts of benzene and 112 parts of potassium hydroxide at 50-80 C., 152 parts of carbon disulfide are slowly added with stirring over a period of several hours at a temperature of 20-30 C. To the resulting orangebrown fluid one adds again, with stirring, gradually 174 parts of propylene oxide at a temperature up to 50 C. After about one hour the addition is complete. The resulting reaction mixture is mixed with 500 parts of benzene, the potassium hydroxide is separated by centrifuging, the residual liquid is neutralized and freed by vacuum distillation from benzene and water. 500 parts of the so-formed xanthic acid derivative are heated under reflux for 4 hours with 180 parts of acetic anhydride. After cooling it is neutralized, washed, extracted with benzene, separated from water and freed of benzene and water under vacuum.

Dithiocarbonic acid-O-(dipropylene glycol-dicyclopentadienol ether)-S-(dipropylene glycol acetic acid ester) FBTA value 370. This compound is obtained by reacting 120 parts of propylene oxide at 130-150 C. with 148 parts of dicyclopentadienol in the presence of 2 parts of sodium. 100 parts of benzene are added, 56 parts of potassium hydroxide are dissolved in the resulting mixture at 50-80 C. and 76 parts of carbon disulfide are added slowly with stirring at 20-30 C. The xanthogenate which forms during several hours is gradually reacted with 125-135 parts of propylene oxide, the reaction mixture is then neutralized and freed from benzene and water by vacuum distillation. 456 parts of the so-formed reaction product are heated under reflux for four hours with 102 parts of acetic anhydride, cooled, Washed with water, extracted with benzene, separated from water and benzene.

Dithiocarbonic acid-O-(pentapropylene glycol octylphenol ether)-S-(propylene glycol acetic acid ester) FBTA value 270. This compound is obtained by reacting 206 parts of octylphenol with 2 parts of sodium hydroxide as catalyzer with 262 parts of propylene oxide, the reaction mixture is diluted with 100 parts of benzene and 56 parts of potassium hydroxide are dissolved in the resulting mixture with heating. Then 76 parts of carbon disulfide are slowly introduced at 30 C. followed by several hours standing for completion of the reaction. Then parts of propylene oxide are gradually introduced, the temperature of the mixture rising to about 50 C. resulting in the addition of 1 mol of propylene oxide. The reaction mixture is worked up. 286 parts of the reaction product are heated under reflux for four hours with 51 parts of acetic anhydride, cooled, washed with water, extracted with benzene, separated from water and benzene.

Dithiocarbonic acid O (monopropylene-tert.-butylcresol ether)-S-(propylene glycol ethyl butyric acid ester) FBTA value 270. This compound is obtained by reacting 80 parts of propylene oxide and 164 parts of the condensation product of isobutylene and commercial cresol in the presence of 2 parts of sodium as catalyzer at 130-l40 C. One then dilutes the mixture with parts of benzene, dissolves 56 parts of potassium hydroxide in the mixture at 50-80 C. and then introduces 76 parts of carbon disulfide gradually at 30 C. After a few hours 80 parts of propylene oxide are gradually added. After the addition of 300 parts of benzene and separation of potassium hydroxide and purification 345 parts of the reaction product are esterified with parts of 2-ethylbutyric acid in the presence of a usual esterification catalyst.

5 6 We claim: ether and ester radicals, n and q are whole numbers from Lubricating composition comprising a lubricant vehicle 1 to 20 and m and p are Whole numbers from 2 to 4. consisting of mineral oil and about 1% to 10% by weight of a polyalkylene glycol xanthic acid derivative References Cited in the of this Patent of the general formula 5 UNITED STATES PATENTS 2,161,584 Moran et al. June 6, 1939 R o [(01% if s 1 2,528,773 Norris Nov. 7, 1950 S 2,694,682 Hal-1e Nov. 16, 1954 in which R stands for an aliphatic, cycloaliphatic, arali- 2,721,178 Harle Oct. 18, 1955 phatic, aromatic, heterocyclic and acyl residue, X stands 10 for a member of the group consisting of hydrogen and 

